High-latitude freeze and thaw states detection using satellite-based microwave land surface emissivity estimates

摘要

Freeze and thaw (FT) processes have profound impact on the terrestrial water cycle, net primary productivity, carbon cycle, surface energy budget and hence the global climate system. The available passive microwave based FT states data are basically developed from brightness temperatures, which themselves affected by atmospheric water vapor content. Since land surface emissivity estimates derived from passive microwave observations are free from atmospheric effects, the use of land emissivity in FT states detection is promising. The objective of this study is to estimate land surface emissivity from the Advanced Microwave Scanning Radiometer-2 observations and to investigate its potential for high-latitude FT states detection. The instantaneous land surface emissivity is computed using an improved algorithm along with near-simultaneous ancillary data sets. The difference of estimated land emissivity between higher and lower frequency channels shows great potential for FT states detection.